Cellular-Only Substitution in the United States as Lifestyle Adoption
Implications for Telephone Survey Coverage
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Historically, the coverage bias from excluding the United States cell-only population from survey samples has been minimal due to the relatively small size of this group. However, the unrelenting growth of this segment has sparked growing concern that telephone surveys of the general public in the United States will become increasingly subject to coverage bias. While there is evidence that demographic weighting can be used to eliminate this bias, the availability of the weights lag behind the rapidly changing cell-only population. To explain the extent of the problem, we propose a reliable model to forecast cell-only population size and demographics. This model posits that a stable behavioral process, the rate of habit retention, can be estimated from prior wireless lifestyle adoption in the United States and may also describe adoption of the cell-only lifestyle. Using measures of incentive and habituation, we test this assumption by predicting changes in the cell-only population size and changes in age demographics. The accuracy of predictions confirms the two adoption behaviors are similar. We then develop forecasts of age demographics through 2009, and show how cell-only lifestyle adoption leads to potential coverage bias that is better addressed through this type of modeling rather than weighting from historical data.
JOHN EHLEN is with Applied Econometrics West, PO Box 1128, Fraser, CO 80442, USA; e-mail: jehlen{at}yahoo.com.
PATRICK EHLEN is with the Center for the Study of Language and Information, Stanford University, Cordura Hall, 210 Panama Street, Stanford, CA 94305, USA; e-mail: ehlen{at}stanford.edu. The authors wish to thank Paul Lavarakas and three anonymous reviewers for their insightful comments.